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Apr

10

SPREE Seminar: Jean Sulem

McCormick - Civil and Environmental Engineering

11:00 AMA230, Technological Institute

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Multi-Physics Couplings and Strain Localization in Seismic Faults

AbstractField observations of exhumed mature faults and outcrops, i.e. faults that have experienced a large slip, have evidenced that shear deformation is often localized in very narrow slip zones. This strain localization is seen as the result of various weakening mechanisms induced during seismic slip. These weakening mechanisms may correspond to a mechanical degradation of the rock properties (micro-cracking, grain crushing and grain size reduction…), but various other physical processes can be responsible for it. The effect of shear heating in a fluid saturated fault zone leads to pore-fluid pressurization due to the discrepancy between the thermal expansion of water and solid grains. Chemical reactions such as dissolution/precipitation, mineral transformation at high temperature (dehydration of minerals, decomposition of carbonates, …) affect the solid phase of the rock, sometimes release a new fluid phase in the system and can induce a positive feedback in the progressive mechanical degradation. The width of the deforming zone is actually a key parameter, as narrow deforming zones concentrate the frictional heating, which leads to large temperature rises and thus to more rapid weakening. It also controls the multi-physics couplings which occur during dynamic slip. Thermo-chemo-mechanical couplings are nowadays more and more identified as factors that play a central role in the mechanical behavior and the evolution of localized deformation zones. Important challenges and questions are still open, which span from the qualitative understanding of the main phenomena to their quantitative description and observation.

In this talk, we will present some recent results on analytical and numerical modelling of strain localization processes under multi-physical couplings and discuss the geophysical implications of these instabilities for earthquakes nucleation.

BioJean Sulem is Professor at Ecole des Ponts ParisTech, and Research Director. He is leading the Geotechnical Group CERMES at Laboratoire Navier. His research interests are related to Bifurcation Theory applied to stability and strain localisation analyses, Constitutive Modelling of geomaterials, Experimental Rock Mechanics, Thermo-Hydro-Mechanical Behaviour of Geomaterials with applications to Tunnelling, Petroleum Engineering, Deep Geological Storage, Fault Mechanics.

Jean Sulem is a member of the Advisory Board of several scientific journals and Associate Editor to Rock Mechanics and Rock Engineering. Since 2016, he is the President of the French Society of Rock Mechanics. In 2018, Jean Sulem received the Vardoulakis lecture Award from the University of Minnesota.

SPREE Seminar: Alexander Handwerger

McCormick - Civil and Environmental Engineering

11:00 AMA230, Technological Institute

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Widespread Acceleration of Slow-Moving Landslides in California Due to Extreme Rainfall

AbstractEpisodically to continuously active slow-moving landslides are driven by precipitation. These landslides cause significant erosion and pose a major natural hazard that can damage infrastructure and threaten life. Climate change, which is altering both the frequency and magnitude of precipitation worldwide, is therefore predicted to have a major impact on landslides. Here we examine the behavior of hundreds of slow-moving landslides in northern California in response to large changes in annual precipitation that occurred between 2016 and 2018. We quantify the landslide displacement using repeat-pass radar interferometry and pixel offset tracking techniques on data from the airborne NASA/JPL Uninhabited Aerial Vehicle Synthetic Aperture Radar. We found that 312 landslides were moving due to extreme rainfall during 2017, compared to 119 during 2016, which was the final year of a historic multi-year drought. However, with a return to below average rainfall in 2018, only 146 landslides remained in motion. The increased landslide frequency during 2017 was accommodated by landslides that were smaller (area < 7 x 105 m2) than the landslides that remained active between 2016 and 2018. Furthermore, by examining a subset of 51 landslides, we found that 49 had increased velocities during 2017 when compared to 2016. Our results show that slow-moving landslides are sensitive to rapid changes in precipitation, particularly the smaller (and thinner) landslides that likely experience larger hydrologic changes. Based on future predictions of precipitation over the next century in California, we hypothesize that there will be profound changes in landslide behavior.

BioAlexander Handwerger is a NASA Postdoctoral Program Fellow at the Jet Propulsion Laboratory, California Institute of Technology.

SPREE Seminar: Roman Makhnenko

McCormick - Civil and Environmental Engineering

11:00 AMA230, Technological Institute

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Poroviscoelastic Behavior of Sedimentary Rock

AbstractThe success of geo-energy applications such as petroleum recovery or geological storage of CO2 depends on properly addressing the physical coupling between the pore fluid diffusion and mechanical deformation of the subsurface rock. Constitutive models should include short-term hydromechanical interactions and long-term behavior, and should incorporate the principles behind the mathematical models for poroelastic and poroviscoelastic responses. In this work, the time-dependent response of fluid-filled sedimentary rock at room temperature and isotropic stress states is experimentally quantified. Drained, undrained, and unjacketed geomechanical tests are performed to measure the poroelastic parameters for Berea sandstone, Apulian limestone, and Opalinus clay (shale). A poroviscous model parameter, the bulk viscosity, is included in the constitutive relationships and is estimated under constant isotropic stress conditions from time-dependent deformation of rock in the drained and undrained regimes for timescales on the order of days. The bulk viscosity is found to be ~ 1015-1016 Pa•s and it decreases with an increase in pore pressure despite a corresponding decrease in the effective stress. In the long term, fluid pressure can asymptotically approach minimum principal stress, which in natural reservoirs may lead to liquefaction or rock embrittlement, causing slip instabilities and earthquakes and creating high-permeability channels in low-permeable rock.

BioRoman Makhnenko is an assistant professor in the Department of Civil and Environmental Engineering at the University of Illinois at Urbana-Champaign. Roman obtained his BS (2007) in mechanics and applied mathematics at Lomonosov Moscow State University (Russia) and his MS (2009) and PhD (2013) degrees in geological and civil engineering from the University of Minnesota – Twin Cities. From 2013 to 2016, Dr. Makhnenko worked as a postdoctoral researcher and lecturer at the Swiss Federal Institute of Technology in Lausanne (EPFL, Switzerland) on the project related to assessment of geological storage of CO2. Currently, Roman is developing a rock mechanics program at Illinois that includes modern high-pressure/high-temperature rock testing facilities and new graduate and undergraduate courses on the topic.

Whole-Brain Leadership for PhD Students Seminar Series: Ken Alder

Join Northwestern Engineering for the 2018-19 seminar series featuring lunchtime presentations by faculty from outside the McCormick School of Engineering and Applied Science. Broaden your horizons by listening to speakers from disciplines such as theatre, economics, law, and philosophy.

Speaker: Ken AlderProfessor of History and Milton H. Wilson Professor in the HumanitiesJudd A. and Marjorie Weinberg College of Arts and Sciences

SPREE Seminar: Dan Negrut

Billion-Degree of Freedom Computational Dynamics: From Granular Flows to 3D Printing and on to River Fording Simulation

AbstractThis talk will focus on how a Lagrangian perspective on dynamics is used to capture the time evolution of complex systems, e.g., granular flows, fluid-solid interaction problems, etc. In this context, the aspects that turn out to be more challenging are tied to the handling of friction, contact, geometry, large deformations and numerical solution scaling. The talk will highlight modeling and numerical solution techniques developed to address several of these challenges. Our solution methodology contributions have been implemented in an open-source simulation platform called Chrono, which is available on GitHub and used by hundreds of individuals to analyze large multi-physics dynamics problems. The talk will touch on several applications tied to granular dynamics, 3D printing and additive manufacturing, robotics, and ground vehicle mobility.

BioDan Negrut received his Mechanical Engineering Ph.D. in 1998 from the University of Iowa under the supervision of Professor Edward J. Haug. He spent six years working for Mechanical Dynamics, Inc., a software company in Ann Arbor, Michigan. In 2004 he served as an Adjunct Assistant Professor in the Department of Mathematics at the University of Michigan, Ann Arbor. He spent 2005 as a Visiting Scientist at Argonne National Laboratory in the Mathematics and Computer Science Division. At the end of 2005 Dan joined the Mechanical Engineering faculty at the University of Wisconsin-Madison. His interests are in Computational Science and he leads the Simulation-Based Engineering Lab (http://sbel.wisc.edu). Lab sponsors include US Army TARDEC, US Army ERDC, Army Research Office, and National Science Foundation. The lab’s projects focus on high performance computing, computational dynamics, terramechanics, robotics, and fluid-solid interaction problems. Dr. Negrut received in 2009 a National Science Foundation Career Award. Since 2010 he is an NVIDIA CUDA Fellow. He is one of the technical leads of Project Chrono, an open source physics-based simulation engine (http://www.projectchrono.org/).

Whole-Brain Leadership for PhD Students Seminar Series: Shari Diamond

Join Northwestern Engineering for the 2018-19 seminar series featuring lunchtime presentations by faculty from outside the McCormick School of Engineering and Applied Science. Broaden your horizons by listening to speakers from disciplines such as theatre, economics, law, and philosophy.

Speaker: Shari DiamondHoward J. Trienens Professor of Law and Professor of PsychologyPritzker School of Law

SPREE Seminar: Gary Klein

McCormick - Civil and Environmental Engineering

11:00 AMA230, Technological Institute

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Shear in Discontinuity Regions: Planned Changes for the Structural Concrete Building Code

AbstractSince its introduction into the ACI 318 code in 2002, the strut-and-tie method has been based on the premise that strength is sufficient if the idealized truss model is in equilibrium with the applied load without exceeding the capacity of struts, ties, and nodes. However, in spite of low strut efficiency factors for so-called bottle-shaped struts, the strut-and-tie method can be unconservative. Struts are not weaker because they are bottle-shaped; rather, the apparent weakness is due to shear failure where struts cross a diagonal tension field. Unless minimum distributed reinforcement is provided, discontinuity regions designed using the strut-and-tie method should be separately checked for shear strength, considering both strut angle and size effect. Furthermore, minimum distributed reinforcement should be provided unless struts are laterally confined. This presentation describes the development of new ACI 318 code requirements for shear design of discontinuity regions using the strut-and-tie method.

BioGary Klein, is Executive Vice President and Senior Principal at Wiss, Janney, Elstner Associates, in Northbrook, Illinois. Mr. Klein is a licensed structural engineer with more than 40 years of experience in failure investigation and structural research. He a long-time member of ACI Committee 318, Structural Concrete Building Code and 445, Shear and Torsion. Research interests include behavior and design of precast concrete elements and discontinuity regions in structural concrete. Honors include ACI’s Wason and Charles S. Whitney medals as well as election to the National Academy of Engineering.

EES Seminar: Morgan Petrovich

Metagenomics-Guided Analysis of Antibiotic and Production Genes, Mobile Genetic Elements, and Viruses in Wastewater Treatment Bioreactors

Abstract:Microbial communities play a critical role in wastewater treatment processes by aiding in transformations of nutrients and other chemicals in wastewater, therefore reducing the impact of municipal and industrial discharges to the environment. Bacteria in wastewater treatment systems are also known to harbor genetic pollutants such as antibiotic resistance genes (ARGs) which can be transferred between bacteria. These ARGs may pose significant threats to public health and can pass through wastewater treatment plants (WWTPs) then ultimately migrate into lakes and rivers through release of effluent. My research focuses on understanding composition and fate of these genetic pollutants throughout wastewater treatment bioprocesses, as well on viral composition of wastewater. This involves application of a wide range of shotgun metagenomics and bioinformatics tools to investigate abundance, mobilization, and spatial distribution of genes in WWTP bioreactors. Using these techniques, we showed that ARG relative abundance in two full-scale municipal WWTPs declined by over 90% between influent and effluent, demonstrating robust removal in conventional suspended growth and biofilm-based bioprocesses. However, ARGs that were released to a receiving water body (Lake Michigan) were much more likely to be associated with markers for mobile genetic elements than those in raw influent, indicating a potential for horizontal gene transfer in natural environments. Our results also revealed a diverse viral community associated with bacterial taxa in this system. In a pilot-scale hospital wastewater treatment and water reuse system in Israel, ARG removal efficiency was significantly lower. In all of the WWTPs studied, ARGs corresponding to antibiotic classes considered to be critically important in clinical settings were identified. Bacteria hosting viruses and bacteria harboring ARGs were found to be more taxonomically similar to one another than to total bacterial populations in hospital wastewater. Finally, I investigated microscale spatial stratification of ARGs in mixed culture biofilms similar to those commonly used in wastewater treatment biofilm reactors. Several targeted ARGs and a gene commonly associated with ARG transfer between bacteria were found to have greatest relative abundances in top layers of biofilms which are most likely to detach and move downstream throughout treatment processes and ultimately into effluent. Overall, my work shows that both ARGs and viruses are diverse and abundant throughout different types of wastewater treatment systems and suggests that ARGs exhibit significant mobilization in WWTPs.

BioMorgan Petrovich is a fifth year PhD student in the Wells Group in the Department of Civil and Environmental Engineering at Northwestern University. Her research focuses on genetic pollutants and microbial community structure in wastewater treatment systems. She graduated from UC Berkeley with a B.A. in Landscape Architecture and Environmental Planning, and received her M.S. in Civil and Environmental Engineering from Northwestern University.

SPREE Seminar: Mohsen Issa

McCormick - Civil and Environmental Engineering

11:00 AMA230, Technological Institute

EVENT DETAILS

Sustainable Structural Concrete for Accelerated Construction

AbstractContemporary construction projects are leaning towards resilient structural solutions with emphasis on sustainable and durable materials. This approach is of great significance for a multitude of applications such as retaining walls, bridge decks, and concrete pavements. Conventional construction practices are associated with several difficulties and drawbacks, such as prolonged site preparation procedures, mitigated work zone safety due to exposure of workers to active traffic, traffic congestion, and environmental costs. As a result, the need for shorter construction periods motivates the development of alternative solutions such as accelerated bridge construction (ABC) techniques. The accelerated construction method incor­porates precast concrete products such as Ultra High Performance Concrete (UHPC) joints, High Performance Concrete bridge decks and fast-setting concrete grouts that combine strength and dura­bility in concrete. From a structural point of view, understanding the effect of materials constituents on the mechanical properties of UHPC and HPC is essential to guar­antee the best working conditions. In addition, sustainable concrete solutions are also focused on reducing the CO2 emission in the cement production and concrete industries, as each ton of cement produced accounts for 0.92 tons of CO2 emissions. This also motivates the need to inspect the standardized ASTM C150 requirements of 10% limestone and inorganic processing additions (IPA) to cement. Limestone and IPA mix design optimization aims to mitigate environmental problems by reducing the amount of raw materials burned to produce cement and to reduce the carbon footprint up to 10% of total CO2 emissions.

BioDr. Mohsen A. Issa received his BSCE, MSCE and Ph.D. degrees from the University of Texas at Arlington, USA and postdoctoral from the University of South Florida, Tampa, USA. Professor Issa served as the Director of Graduate Studies for the Department of Civil and Materials Engineering for 8 years. He is the Director of the Structural and Concrete Research Laboratory at UIC. Professor Issa has been teaching various courses in the field of reinforced and prestressed concrete structures, steel design, bridge design, and concrete materials. Through his research funding, Dr. Issa has graduated 22 Ph.D., 15 Masters graduate students and currently supervising 7 PhD students. Professor Issa has been honored with several teaching and research awards. He is a Fellow of the American Concrete Institute (ACI) and American Society of Civil Engineers (ASCE). He is a registered Structural Engineer in the State of Illinois as well as Professional Engineer in the State of Florida. He has published over 150 papers in reputed refereed journals and proceedings. Dr. Issa has also moderated and organized a large number of technical sessions within the civil engineering infrastructure and made numerous invited keynote lectures and presentations nationally and internationally. Dr. Issa has been the principal investigator for research projects funded by National Science Foundation, Illinois Department of Transportation, Chicago Department of Transportation, Illinois Transportation Research Center, Illinois Center for Transportation, Federal Highway Administration, U.S. Army Construction Engineers Research Laboratories, and other local industries.